Tunbridge Wells Museum & Art Gallery - February 2017

Dinosaur bone

Dinosaur bone

February's Object of the Month has been chosen by work experience student Leah Mitchell. The object is a dinosaur bone previously thought to be the femor of Iguanodon hollingtoniensis.

In the Natural History room of the museum, an enormous, ancient bone rests behind the glass of its display case. The bone is split into three pieces, which lie side by side like a jigsaw puzzle; the lower and central portions of the left femur (or thigh bone) of a dinosaur which roamed the shores of the Wealden Lake some 135 million years ago.

The bone is truly enormous; the length of an adult’s arm and very thick, it gives an impressive indicator of how large the dinosaur itself must once have been. While it now has the glory of a permanent display position in the Natural History room, it was previously displayed on the landing between the museum and art gallery for two months in 2007, and prior to that was stored away in the basement. It was acquired by the museum in 1983 with eight other fossilised bone fragments from the same species of dinosaur, which were found at various local sites – in High Brooms, Tonbridge, Southborough, Chiddingstone, and Hartfield (Sussex). These bone fragments include caudal (tail) vertebrae, a fragment of a radius, a fragment of a humerus, and various portions of femurs.

This particular bone was found in August 1933 at the former High Brooms brickworks pits, where various other similar remains have been found over the years, in the iron-rich Wadhurst Clays – the second oldest geological beds in the area. This species of dinosaur is thought to have existed in considerable numbers in the Lower Cretaceous period around the Wealden Lake – a huge shallow freshwater to brackish (briny, but with less salinity than seawater) lake which existed for 20 million years  over the lands of what is now northern France and southern England, approximately 145 to 125 million years ago.

Iguanodon display in the Museum

Perhaps the most interesting aspect of this collection of bones is that the information provided in the museum’s display was recently challenged. The display labels the bone fragments as belonging to the dinosaur species Iguanodon hollingtoniensis, but in fact very recently this species was reassigned to the genus Huxleysaurus, making the species Huxleysaurus hollingtoniensis. The species was labelled Iguanodon hollingtoniensis by Richard Lydekker in 1889, who named it based on remains found at Hollington near Hastings. In fact, many species were originally classified in the genus Iguanodon, until research in the early 21st century suggested that there was only one well-substantiated species, Iguanodon bernissartensis. The so-called Igunodon hollingtoniensis was named as the new genus Huxleysaurus by Gregory S. Paul in 2012. The generic name honours Thomas Henry Huxley, a 19th century English biologist, both for being “Darwin’s Bulldog” (a passionate and early advocate of Darwin’s theory of evolution) and for coining the term “agnostic”. However, somewhat confusingly, the species Huxleysaurus hollingtoniensis still belongs to the “clade”, or wider biological group, Iguanodontia.

Leah says: "When I was trying to choose an object to write about for this month, my interest was immediately piqued upon seeing this enormous bone. Not only is it visually impressive due to its size, but I found it incredible to imagine that, however long ago, dinosaurs once roamed the ground we walk on today – not some far away rainforest on the other side of the world, as I had always pictured in my mind’s eye, but the local area which is so familiar to me: High Brooms, Tonbridge, Southborough, and so on. I decided to look it up on the museum’s catalogue of objects, and once a little preliminary research revealed that the bone actually belonged to a different species of dinosaur to the one we had previously thought it did, I was fascinated and knew I had something interesting to write about."

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